Clutch suddenly lost all pressure, peddal is permanently stuck on the floor, can lift the pedal but it drops straight back down.
Sounds like what you have is a leaking slave cylinder and that your fluid has all leaked out. If the slave is accessible, pull the boot back off cylinder body and see if it is full of fluid. If you find fluid their you will need to replace it. You are going to also have to bleed the air out once the new cylinder is in stalled. Can be difficult. Will need a friend to pump the clutch peddle. Friend will need to pump peddle very fast several times them hold peddle to floor. When peddle is held to floor is when you open bleeder to allow the air to come out. Close bleeder after a couple of seconds and then repeat. Make sure that you add fluid to the reservoir every couple of times of opening the bleeder. Must pump peddle really fast is key. Clutch peddle should come off floor a ways before clutch started to engauge. If not keep bleeding